He doesn't need a visa. He's allowed to be there for 90 days of tourism http://madrid.usembassy.gov/visas/tr...ut/waiver.html
Also, tell him to check out Pacha, The Empire Hotel, Katra, an old favorite of mine is Pianos. Pianos is in a great neighborhood too. Lots to see and do.
Rockefeller Center is a cool place, the tree should be lit by the time he is there.
South Street Seaport, Brooklyn (Brooklyn Bridge Park) ...
Honestly I could go on forever! And now... I'm officially homesick! HA!
Hope this helps!